Artificial foot



e. E.YANDI w. L. MARKS.

ARTIFICIAL FOOT.

APPLICATION mm AUG.23, 1921.

Patented June 20, 1922.

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umran sTA s PATENT oF cE.

GEORGE 'E. MARKS AND WILLIAM L. MARKS, or sounn BEACH, CONNECTICUT.

ARTIFICIAL FOOT. I

and useful Improvements in Artificial Feet,

of which the following is a specification.

1 The invention pertains to improvements in artificial feet embodying an inelastic core and a body-portion composed of rubber and in the approximate outlineof a human foot.

The present invention embraces certain improvements on the artificial foot made the subject of Letters Patent of the United States No. 546,405 granted to us on September 17 1895, and the object of the present in vention is to provide certain featureswithin the rubber portion of the foot which will improve the wearing qualities of the foot, en- Y hance the comfort of the wearer by an improved action in the rubber-body during the act of walking, assure the correct return to normal position of those portions of the rubber-body which become flexed during the act of walking, prevent lateral distortion of the side portions of the foot, prevent the forward end of the inelastic core, which is usually formed of wood, from undue wear on the rubber-body during walking and generally add to the efiiciency and desirability of the foot.

In accordance with our invention we add two features to the foot of the aforesaid patent, one being a strong cord mattress em bedded within the upper forward portion of the rubber body of the foot and extending rearwardly below the forward end of the inelastic core to take the thrust thereof during the flexing of the foot in the act of walking, and the other feature being a special cord inner sole embedded within the rubber body of the foot and extending lengthwise thereof and composed of two sets of evenly spaced apart strong cords diagonally crossing each other, the meshes or interstices formed by the crossing cords being preferable about one-quarter inch in size and finally completely filled with rubber. The diagonally crossed sets of insole cords when embedded in the foot act not only with the aforesaid upper cord-mattress'to strengthen the foot, but while permitting the flexing of the foot, as in the act of walking, aid'in returning the flexed portion of the foot back to normal position and in addition act, dur- $plecification of Letters Patent.

ing" the lengthwise stretching of the foot during walking, to resist permanent lateral spreading out of the foot'by exerting a distributed pulling stress against the opposite sides of the foot which keeps the rubber body portion in correct relation to the inelastic core and in proper position to best serve the comfort of the wearer. i

The invention will be fully understood from the detailed description hereinafter Patented June 20, 1922.

Application fil ed'Aug'ust 23, 1921. Serial No. 494,692.

presented, reference being had to the accom- V panying drawings, in which Fig..1is a central vertical longitudinal section,'partly'broken away, of a foot constructed in accordance with and embodying the invention;

' Fig. 2 is a detached top view of the upper cord-mattress which we apply within the upper forward portion of the rubber body of the foot and extend the same below the forward portion of the wood or other'inelastic core; I I 1 Fig. 3 is a'bottom view,-partly broken away, of a cord inner sole'embedded within the lower portion of the foot and extending substantially throughout the length and width thereof, and p Fig. 4 is a corresponding view of a cord inner sole presenting a modified arrangement of the cords, the cords in the inner sole shown in Fig. 4: being interlaced instead of lying against one another, as shown in Fig. 3. In the drawings, 10 indicates the foot as a whole, 11 the inelastic cord thereof, usually formed of wood, 12 an exterior covering of vulcanized rubber encasing the foot, 13 a body of spongerubber applied to the core 11 and enclosedby the casing 12 and constituting the body oryielding portion of the foot, and 14a canvas-enclosed spring applied longitudinally of thefoot'and being of the type described in the aforesaid Letters Patent'No. 546,405.

v The essentialfeatures of the present invention reside 'in the cord mattress 15 shown detached in Fig. 2 and in the cord inner sole 16 shown separately in Fig. 3 and in modi-' fied form in Fig. 4c; i

The mattress 15 is initially flat and when in position in the foot extends transversely being curved upwardly below the forward end of said core and then turned downwardly and extended along the upper forward portion-of the foot. The mattress 15 consists of a series of parallel hard-twisted cords17 of strong texture substantially em bedded in pure gum rubber which fills in between and sufiiciently embeds the cords 17 to permit the mattress to be handled as a unit and properly positioned within the sponge rubber 13. The mattress 15 is of great benefit in strengthening the upper forward rubber portion of the foot and in taking the thrusts of and resisting the wearing strains exerted by the forward end of the core 11 during the act of walking. The mattress 15 very greatly aids in preserving the proper outline and integrity of the upper forward portion of the foot and ma terially increases the wearing life of the foot as a whole. The forward end of the core 11 during the act of walking is repeatedly thrust into the rubber below it and to resist destructive action of the core 11 against the rubber is one of the purposes of the mattress 15.

The inner canvas covered spring 14: does not require special description, since said spring and the benefits thereof are disclosed in our aforesaid Letters Patent No. 546,405.

The inner sole 16 conforms in edge outline to the sole outline of thefoot and said inner sole 16 comprises a layer of pure gum rubber 18 and two crossing series of cords 19, 20 which cords are hard-twisted and of strong texture and extend diagonally of the inner sole with the series of cords 19 evenly spaced apart and crossing the series of cords 20 at right angles thereto and which cords 20 are also evenly spaced apart. The layer of rubber 18 partly embeds the cords 19, 20 and holds said cords in proper relation to each other during the application of the inner sole to position within the foot. The meshes formed by the cords 19, 20 are preferably about one-quarter of an inch in size.

In the application of the inner sole 16 to the foot, the rubber layer 18 is at the top, and hence the exposed surfaces of the cords 19, 20 face downwardly. The inner sole 16 is placed against the sponge rubber below the spring 141, and thereafter the outer layer of rubber is applied over thefoot and vulcanized to the shape of the foot andconr pletely encases the inner portions thereof,

the rubber along the sole of the foot merging into the sponge rubberand into the interstices or meshes formed by the crossing of the cords 20. r r

The novel features of the foot reside more particularly in the mattress 15 and inner sole 16, andthese two features of construction when applied within the rubber portion of the foot are of marked advantage thereto. We have referred to some of the advantages of the mattress 15. The inner sole 16 cooperates with the mattress 15 in maintaining the strength and integrity of the forward portion of the foot and especially in preserving the wearing life of the upper forward portion of the foot by resisting those strains which come upon the foot forwardly of the core 11 during the act of walking. The inner sole 16 performs the further duty of aiding in the restoration of the toe portion of the foot to normal position after every action, in walking, fi'exingsaid portion at an angle to the main sole portion of the foot.

The crossed diagonally disposed cords 19, 2O materially strengthen the entire sole portion of the foot and impart a firmness thereto conducive to the comfort of the wearer. During the act of walking, the rubber'body portion of the foot becomes .fiexed and stretched lengthwise,and during this action the lengthwise pull on the inner sole 16 acts through the forward portions of the diagonal cords 19, 20 to draw the rear portions of said cords inwardly, and this results in the strains on the rubber feet being distributed throughout the lower portion of the foot and ina tendency of the cords to draw the sides of the foot inwardly below the core 11, with the result of preventing permanent lateral spread of the foot and in consequence thereof adding to the wearing life of the foot. If the body of the foot should be forced forwardly at its front end, as during theact of walking, the forward stretch of the sole acting through the rubber will pull forwardly on the forward ends of the cords 19, 20, and this strain will be distributed through the lengths of the cords in diagonally opposite directions and the cords will'thus act as a means for distributing the strain throughout the foot and in having their end portions drawn inwardly as well as forwardly, thereby serving to prevent undue lateral spread of the foot and preserving the rubber body portion of the foot from any distortion tending to shorten the period of its practical inner sole which we number 21 and which embodies a layer of rubber 22 and two sets of diagonally crossed cords 23, 24:, these cords in their function, location and arrangement corresponding with the cords 19, 20 described with reference to Fig. 3, the difference between the constructions shown in Figs. 3 and 4 residing in the fact that the cords 23, 24 are interlaced in the formation of the interstices or meshes which receive the rubber. The inner sole 21 performs all of the duties of the inner sole 16 shown in Fig. 3, but we find that with the use of the rubber body holding the cords, the cords arranged upon one another as shown in Fig. 3 are entirely efficient and do not require the lacing indicated by the cords 23, 24: in Fig. 4c.

In both inner sole constructions shown the rubber which fills the meshes of the cords coacts with the cords in restoring the foot to normal position after each flexing thereof during the act of walking. WVhen the front of the foot is bent, as it repeatedly is when the wearer is walking, the rubber in the meshes of the inner sole is placed under an intense pulling tension, the energy of which, when the foot is relieved of the weight of the wearer, acts to draw the cords back to their normal position and assure the return of the front of the foot to its proper lines. The rubber which we primarily apply to the cords in forming the inner sole is not sponge rubber but pure gum rubber in sheet form.

The mattress shown in Fig. 2 may be formed of cords arranged as indicated in Figs. 3 and 4, but we have shown in Fig. 2 a preferred embodiment for the mattress. We may also add that the cording shown in Figs. 3 and 4 may be of net formation in lieu of said cords being initially loosely juxtaposed.

What we claim as our invention and desire to secure by Letters-Patent, is:

1. An artificial foot comprising an inelastic core, a body portion of rubber below and forward of said core and extending from the heel to the toe portion of the foot, and a cord inner sole extending from within the heel to the toe portion of the foot and conforming in outline to the general horizontal outline of the foot, said inner sole being embedded in said body portion and comprising two sets of parallel spaced apart cords of strong texture extending diagonally across each other in opposite directions and forming coarse meshes filled with rubber.

2. An artificial foot comprising an inelastic core, a body portion of rubber below and forward of said core and extending from the heel to the toe portion of the foot, a cord inner sole extending from within the heel to the toe portion of the foot and conforming in outline to the general horizontal outline of the foot, said inner sole being embedded in said body portion and comprising diagonally disposed crossing sets of parallel cords of strong texture spaced apart and forming coarse meshes filled with rubber, and a mattress of cords and rubber located in said body below the forward end of said core to take the thrusts thereof and thence extending forwardly above the forward portion of said inner sole.

3. An artificial foot comprising an inelastic core, a body portion of rubber below and forward of said core and extending from the heel to the toe portion of the foot, a cord inner sole extending from within the heel to the toe portion of the foot and conforming in outline to the general horizontal outline of the foot, said inner sole being embedded in said body portion and comprising diagonally disposed crossing sets of parallel cords of strong texture spaced apart and forming coarse meshes filled with rubber, and a fabric-covered spring of the character described embedded in said rubber body portion above said inner sole and extending from within the heel to the toe portion, of

the foot.

4. An artificial foot comprising an inelastic core, a body portion of rubber below and forward of said core and extending from the heel to the toe portion of the foot, a cord inner sole extending from within the heel to the toe portion of the foot and conforming in outline to the general horizontal outline of the foot, said inner sole being embedded in said body portion and comprising diagonally disposed crossing sets of parallel cords of strong texture spaced apart and forming coarse meshes filled with rubber, a fabric-covered spring of the character described embedded in said rubber body portion above said inner sole and extending from within the heel to the toe portion of the foot, and a mattressof cords and rubber located in said body below the forward end of said core to take the thrusts thereof and thence extending forwardly above the forward portions of said spring and inner sole.

Signed at New York city, in the county of New York and State of New York, this 22nd day of August A. D. 1921.

GEORGE E. MARKS. WILLIAM L. MARKS. 

